A brake mechanism and unwinding device for tension control

Abstract

The application discloses a brake mechanism for tension control, comprising a mounting frame, a pay-off roller rotatably arranged on the mounting frame and used for mounting a label paper cylinder, and a brake mechanism comprising a friction wheel, a friction belt, a first elastic member and a second elastic member, wherein the friction wheel is arranged on the pay-off roller and can rotate with the pay-off roller, the friction belt can be frictionally abutted on a wheel surface of the friction wheel, and the first elastic member and the second elastic member are respectively connected to two ends of the friction belt to keep the friction belt and the friction wheel in a friction state. By adopting the first elastic member and the second elastic member to respectively tension two ends of the friction belt, a stable brake torque is provided based on a flexible body friction Euler formula; during brake release, the unilateral elastic member is lengthened while the other side elastic member is synchronously contracted by a cam, so that the brake force is prevented from suddenly rising and falling, the brake force transition is gentle, the label tension fluctuation amplitude is small, the length of the label that can be stably pulled out at a time is greatly improved, and the label output stability is better.

Description

Technical Field

[0001] The present invention relates in particular to a braking mechanism and unwinding device for tension control. Background Technology

[0002] During the automatic operation of a labeling machine, rolls of label material are mounted on the unwinding spindle, and the downstream traction mechanism pulls the label tape to achieve continuous label dispensing. To avoid problems such as uncontrolled spinning of the label roll due to inertia, label tape tension fluctuations causing label dispensing deviation, and material roll scattering, the unwinding spindle is usually equipped with a passive braking mechanism. This mechanism relies on frictional resistance to apply a braking torque to the spindle. When the label tape tension reaches a set threshold, the brake is released, allowing the label tape tension to be maintained within a reasonable range. This type of purely mechanical passive braking structure requires no additional power input and is a widely adopted tension control solution in the current labeling unwinding field.

[0003] However, existing passive tension braking mechanisms have significant limitations in practical applications. The outer diameter of the label roll decreases continuously as the label tape is continuously output. Under the premise of keeping the braking torque constant, the shrinking roll diameter will directly lead to a continuous increase in the actual tension of the label tape, requiring a corresponding increase in the braking release frequency to maintain tension stability. However, the tension release threshold and the single label length of the existing mechanism cannot be adjusted synchronously, resulting in poor tension self-adaptation. Typically, after the label roll is used, the tension will continue to rise, and the label tape will become tighter and tighter, which can easily cause the label tape to break. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a braking mechanism and unwinding device for tension control.

[0005] A braking mechanism for tension control, comprising:

[0006] Mounting rack;

[0007] The unwinding roller is rotatably mounted on the mounting frame for mounting label paper tubes;

[0008] The braking mechanism includes a friction wheel, a friction belt, a first elastic member, and a second elastic member. The friction wheel is mounted on the unwinding roller and can rotate with the unwinding roller. The friction belt can rub against the surface of the friction wheel. The first elastic member and the second elastic member are respectively connected to both ends of the friction belt so that the friction belt and the friction wheel maintain a frictional contact.

[0009] In one embodiment, the braking mechanism further includes a tension swing arm, which is rotatably mounted on the mounting frame via a rotating shaft. A first guide wheel is provided on the tension swing arm for the end of the label paper to be wound around. A cam is provided at the rotating shaft. The cam can rotate and press against a first elastic member or a second elastic member to release the tension at one end of the friction band. A third elastic member is connected between the tension swing arm and the mounting frame. The third elastic member keeps the cam in a disengaged state from pressing against the first or second elastic member.

[0010] In one embodiment, the first elastic member includes a first tension spring and a first connecting block. The first connecting block is connected to one end of the friction belt, and the first tension spring is connected between the first connecting block and the mounting bracket. The first tension spring initially maintains a tension force on the first connecting block.

[0011] In one embodiment, the second elastic member includes a second tension spring and a second connecting block. The second connecting block is connected to one end of the friction belt and is mounted on the mounting bracket by a slide rail slider. The second tension spring is connected between the second connecting block and the mounting bracket, and initially maintains a tension force on the second connecting block. The cam can rotate and press against the second connecting block, causing the second connecting block to move away from the second tension spring.

[0012] In one embodiment, the second connecting block is provided with a protrusion that abuts against the surface of the cam wheel, and the second connecting block is provided with an adjustment structure that can adjust the protrusion relative to its outward protrusion length.

[0013] In one embodiment, the adjustment structure includes a vertical long groove extending through the protrusion, and the second connecting block has two or more screw holes located in the vertical long groove, with fastening screws threadedly connected to each screw hole, and the fastening screws can be pressed onto the protrusion along the thread displacement.

[0014] In one embodiment, the third elastic member includes a third tension spring and a limiting post. The third tension spring is connected between the mounting frame and the tension swing rod. The limiting post is disposed on one side of the mounting frame. The tension swing rod is kept in contact with the limiting post by the tension of the third tension spring.

[0015] In one embodiment, the friction wheel is detachably mounted to one end of the unwinding roller.

[0016] In one embodiment, the unwinding roller is provided with an anti-rotation mechanism;

[0017] An anti-rotation mechanism includes a base, the center of which is provided with a mounting through hole for mounting on an unwinding roller, and a plurality of elastic pawl units are evenly arranged circumferentially inside the base.

[0018] The elastic pawl unit includes a pawl, a first hinge pin, a second hinge pin, a spring pin, and an elastic element. The first hinge pin is mounted on a base, and its axis is arranged parallel to the central axis of the base. One end of the pawl is hinged to the first hinge pin and can swing inward and outward along the radial direction of the base. The second hinge pin extends parallel to and in the same direction as the first hinge pin, and passes through the part of the pawl away from the first hinge pin and between the second hinge pin and the spring pin. The pawl can drive the spring pin to move synchronously during swinging through the second hinge pin, and the pawl and the spring pin can rotate relative to each other around the second hinge pin. An elastic element is provided between the spring pin and the inner wall of the base. The elastic pawl unit also includes a limiting pin, which is located on the radial outer side of the pawl to limit the maximum outward swing stroke of the pawl. The base is provided with mounting grooves corresponding to each elastic pawl unit, and the mounting grooves have openings facing the outer periphery of the base to allow the pawl to swing outward.

[0019] An unwinding device includes: a traction device and the aforementioned braking mechanism for tension control, wherein a plurality of second guide wheels are spaced apart on the mounting frame, and the end of the label paper can be sequentially wound around the first guide wheel and the plurality of second guide wheels and connected to the traction device.

[0020] In summary, the advantages of this invention over the prior art are:

[0021] This invention employs a first elastic component and a second elastic component to tension both ends of the friction belt, providing a stable braking torque based on the Euler formula for flexible body friction. During the braking release process, while one side of the elastic component is stretched by the cam, the other side of the elastic component contracts synchronously, avoiding sudden increases and decreases in braking force, resulting in a smooth transition of braking force, small fluctuations in the tension of the strip, and a significant increase in the length of the strip that can be stably pulled out in a single operation, thus improving the stability of strip delivery.

[0022] Furthermore, by sensing the tension of the label tape in real time through the tension swing arm, and dynamically adjusting the tension of the friction belt through the linkage cam, the braking release frequency and braking force can be automatically matched as the outer diameter of the label roll continues to decrease. This breaks the traditional law that the tension of the label tape continuously increases as the roll diameter decreases under constant braking torque, and maintains stable tension throughout the entire life cycle of the label roll, completely solving the problem of the label roll becoming tighter and tighter and frequently breaking after use. Attached Figure Description

[0023] Figure 1 This is a front view of a braking mechanism for tension control in one embodiment of the present invention;

[0024] Figure 2 This is a front view of an unwinding device according to one embodiment of the present invention;

[0025] Figure 3 This is one perspective view of an unwinding device according to one embodiment of the present invention;

[0026] Figure 4 This is a second perspective view of an unwinding device according to one embodiment of the present invention;

[0027] Figure 5 This is one of the exploded views of a braking mechanism for tension control according to an embodiment of the present invention;

[0028] Figure 6 This is a second exploded view of a braking mechanism for tension control according to one embodiment of the present invention;

[0029] Figure 7 This is an exploded view (3) of a braking mechanism for tension control according to one embodiment of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0031] like Figures 1 to 7 The present invention preferably provides a braking mechanism for tension control, comprising: a mounting frame 31; an unwinding roller 32 rotatably mounted on the mounting frame 31 for mounting label paper tubes; and a braking mechanism comprising a friction wheel 33, a friction belt 34, a first elastic member 35, and a second elastic member 36. The friction wheel 33 is mounted on the unwinding roller 32 and can rotate with the unwinding roller 32. The friction belt 34 can rub against the surface of the friction wheel 33. The first elastic member 35 and the second elastic member 36 are respectively connected to both ends of the friction belt 34 so that the friction belt 34 and the friction wheel 33 maintain a frictional contact.

[0032] Specifically, the unwind roller is mounted on the mounting frame to support the label paper tube and the material roll; the friction wheel is coaxially fixed and rotates synchronously with the unwind roller, and the friction belt surrounds and abuts against the wheel surface of the friction wheel to form a flexible friction pair with a fixed wrap angle.

[0033] According to Euler's formula for friction of flexible bodies, the tension F1 on the tight side and the tension F2 on the slack side of the friction band satisfy the following mechanical relationship:

[0034] Where: f is the coefficient of friction between the friction belt and the friction wheel, α is the wrap angle (in radians) of the friction belt on the friction wheel, and e is the base of the natural logarithm. The tension difference between the two ends of the friction belt acts on the friction wheel, forming a braking friction torque. (r is the radius of the friction wheel), which prevents the unwinding roller from rotating freely due to inertia.

[0035] The first and second elastic components apply continuous tension to both ends of the friction belt, creating a slack side and a tight side, ensuring the friction belt always grips the friction wheel. Based on the Euler friction principle, a constant basic braking friction torque is generated, providing basic braking resistance for label unwinding and maintaining the initial tension of the label tape. In this mechanism, the wrap angle α of the friction belt and the coefficient of friction f remain constant, and the braking torque can be precisely adjusted by changing the tension at the ends of the friction belt.

[0036] The core premise for applying Euler's formula is that the wrap angle α remains constant. The two ends of the friction belt are connected tangentially along the friction wheel, and the position of the connection point is fixed. Only the magnitude of the tension changes, and the contact wrap angle does not change with the release of the brake.

[0037] In the unwinding rotation direction, the first elastic member side of the friction belt is the tight side F1, and the second elastic member side is the loose side F2.

[0038] Furthermore, the braking mechanism also includes a tension swing arm 37, which is rotatably mounted on the mounting frame 31 via a rotating shaft 38. A first guide wheel 39 for the end of the label paper to be wound around is provided on the tension swing arm 37, and a cam 40 is provided at the rotating shaft 38. The cam 40 can rotate and press against the first elastic member 35 or the second elastic member 36 to release the tension at one end of the friction band 34. A third elastic member 41 is connected between the tension swing arm 37 and the mounting frame 31. The third elastic member 41 keeps the cam 40 in a disengaged state from pressing against the first elastic member 35 or the second elastic member 36.

[0039] Specifically, the third elastic component applies a reset force to the tension swing arm, so that the cam on the rotating shaft is initially in a state of disengagement from the pressing elastic component. At this time, the tension at both ends of the friction belt is stable, and the braking mechanism maintains the rated torque.

[0040] When the downstream traction device pulls the label tape and the label tape tension increases, the force of the label tape on the first guide wheel causes the tension swing arm to swing around the rotating shaft, and the rotating shaft synchronously drives the cam to rotate. When the cam rotates to the lifting section, it presses against the elastic component on the corresponding side, releasing the tension force at that end of the friction belt, thus reducing the slack side tension F2. According to Euler's formula for friction of flexible bodies, the tight side tension F1 will decrease synchronously with the slack side tension F2, the tension difference (F1-F2) at both ends of the friction belt decreases, the braking torque decreases accordingly, and the unwinding roller can rotate to release the label tape.

[0041] As the tension of the strip drops after unwinding, the third elastic component drives the tension swing arm and cam to reset, the friction belt tension returns to its initial value, the braking torque increases and restricts the rotation of the unwinding roller again, thus achieving dynamic balance adjustment of tension in this cycle.

[0042] Furthermore, the first elastic member 35 includes a first tension spring 42 and a first connecting block 43. The first connecting block 43 is connected to one end of the friction belt 34, and the first tension spring 42 is connected between the first connecting block 43 and the mounting bracket 31. The first tension spring 42 initially maintains a tension force on the first connecting block 43.

[0043] Specifically, the first tension spring is connected to one end of the friction belt through the first connecting block. In the initial assembly state, the first tension spring is in a pre-stretched state and continuously applies a stable tension force to the first connecting block, thereby pulling the corresponding end of the friction belt to form the tight side F1 tension input end of the friction belt, providing a constant basic tension force for the friction belt, ensuring that a stable friction braking pair is formed between the friction belt and the friction wheel, and providing basic tension conditions for the establishment of Euler friction braking torque.

[0044] Furthermore, the second elastic member 36 includes a second tension spring 44 and a second connecting block 45. The second connecting block 45 is connected to one end of the friction belt 34 and is mounted on the mounting bracket 31 by means of a slide rail slider. The second tension spring 44 is connected between the second connecting block 45 and the mounting bracket 31, and the second tension spring 44 initially maintains a tension force on the second connecting block 45. The cam 40 can rotate and press against the second connecting block 45, causing the second connecting block 45 to move away from the second tension spring 44.

[0045] Specifically, the second tension spring is connected to the other end of the friction belt through the second connecting block. In the initial state, the second tension spring is in a pre-stretched state, pulling the second connecting block along the slide rail slider pair to maintain the initial position, so that the friction belt at this end is kept taut. The first tension spring and the second tension spring work together to form a stable tension difference at both ends of the friction belt, generating the rated basic braking torque based on the Euler formula for flexible body friction.

[0046] When the cam rotates with the tension lever, the cam wheel surface presses against the second connecting block, pushing the second connecting block to slide along the slide rail away from the second tension spring. The second tension spring is further stretched, and the slack side tension F2 at that end of the friction band decreases simultaneously; according to Euler's formula... As the tension F1 on the tight side decreases proportionally with F2, the tension difference between the two ends of the friction band decreases, the braking torque decreases, and the brake release is achieved.

[0047] During this process, the first tension spring contracts slightly in sync with the change in friction band tension, offsetting part of the tension reduction and preventing a sudden drop in the slack side tension F2 that would cause a sharp drop in braking torque, thus ensuring a smooth transition of braking force. After the cam resets, the elastic tension of the second tension spring drives the second connecting block to reset along the slide rail, and the friction band is re-tensioned, restoring the basic braking torque.

[0048] Furthermore, the second connecting block 45 is provided with a protrusion 46 that abuts against the wheel surface of the cam 40, and the second connecting block 45 is provided with an adjustment structure 47 that can adjust the protrusion 46 relative to its outward protrusion length.

[0049] Specifically, the protrusion on the second connecting block, as a direct force-bearing component, contacts the cam wheel surface and bears the pressure of the cam. By adjusting the protrusion length relative to the second connecting block through the adjustment structure, the rotation angle at which the cam and the protrusion begin to contact can be changed, thereby changing the swing angle threshold of the tension lever triggering brake release. At the same time, the maximum displacement stroke of the second connecting block is changed, ultimately changing the reduction of the slack side tension F2 and the adjustment range of the braking torque, thus achieving synchronous adjustment of the tension threshold of brake release and the single-stroke length.

[0050] Furthermore, the adjustment structure 47 includes a vertical long groove 48 that runs through the protrusion 46. The second connecting block 45 has two or more screw holes located in the vertical long groove 48. Fastening screws are threadedly connected to the screw holes one by one. The fastening screws can be pressed onto the protrusion 46 along the thread displacement.

[0051] Specifically, the protrusion overlaps the second connecting block via a vertical groove. When the fastening screw is loosened, the protrusion can slide up and down along the vertical groove to adjust its outward protrusion length relative to the second connecting block. After adjusting to the target position, the fastening screw is tightened, and the end of the screw presses against the surface of the protrusion to achieve locking and fixation. This structure has a simple and intuitive adjustment method and can accurately match the tension and label dispensing length requirements of different label rolls.

[0052] Furthermore, the third elastic component 41 includes a third tension spring 49 and a limiting post 50. The third tension spring 49 is connected between the mounting frame 31 and the tension swing rod 37. The limiting post 50 is disposed on one side of the mounting frame 31. The tension swing rod 37 is kept in a contacting state with the limiting post 50 by the tension of the third tension spring 49.

[0053] Specifically, the third tension spring is connected between the mounting bracket and the tension swing arm, continuously applying a reset force to the tension swing arm, causing it to tend to swing back to its initial position. The limiting post is fixed on the mounting bracket, serving as a limiting component for the initial position of the tension swing arm. Under the tension of the third tension spring, the tension swing arm abuts against the limiting post, precisely limiting the initial angle position of the cam and ensuring that the cam will not accidentally press against the second connecting block in the initial state, thus ensuring that the initial braking torque of the braking mechanism is stable and reliable.

[0054] Furthermore, the friction wheel 33 is detachably mounted on one end of the unwinding roller 32.

[0055] Specifically, the friction wheel is detachably installed at the end of the unwinding roll. When the friction wheel wears out after long-term use, or when it is necessary to replace it with a friction wheel of different diameter and surface material to adjust the friction coefficient f and the braking torque reference value, it can be directly disassembled and replaced without disassembling the entire unwinding roll and braking mechanism, thus reducing maintenance difficulty and replacement cost.

[0056] Furthermore, the unwinding roller 32 is provided with an anti-rotation mechanism; the anti-rotation mechanism includes a base 1, the base 1 having a mounting through hole 10 at its center for mounting on the unwinding roller 32, and a plurality of elastic pawl units evenly arranged circumferentially inside the base 1; the elastic pawl unit includes a pawl 21, a first hinge pin 22, a second hinge pin 23, a spring pin 24, and an elastic element 25; the first hinge pin 22 is mounted on the base 1, and its axis is arranged parallel to the central axial direction of the base 1; one end of the pawl 21 is hinged to the first hinge pin 22 and can swing inward and outward along the radial direction of the base 1; the second hinge pin 23 extends parallel to and in the same direction as the first hinge pin 22, the second hinge pin 24... 3. The portion of the pawl 21 away from the first hinge pin 22 is connected to the spring pin 24; the pawl 21 can drive the spring pin 24 to move synchronously when swinging through the second hinge pin 23, and the pawl 21 and the spring pin 24 can rotate relative to each other around the second hinge pin 23; an elastic element 25 is provided between the spring pin 24 and the inner wall of the base 1, and the elastic pawl unit also includes a limiting pin 26, which is located on the radially outer side of the pawl 21 to limit the maximum outward swing stroke of the pawl 21; the base 1 is provided with mounting grooves 11 corresponding to each elastic pawl unit, and the mounting grooves 11 are open towards the outer periphery of the base 1 to allow the pawl 21 to swing outward.

[0057] Specifically, the base is fixedly mounted on the unwinding roller through the central mounting hole and rotates synchronously with the unwinding roller. When the label tube is sleeved on the outside of the anti-rotation mechanism, the inner wall of the tube presses the pawls inward, and the pawls swing radially inward around the first hinge pin. The second hinge pin drives the spring pin to move synchronously, compressing the elastic element. The elastic reaction force of the elastic element pushes the spring pin, which is transmitted through the second hinge pin to make the pawls tend to swing outward, thereby pressing the outer end of the pawls against the inner wall of the tube, realizing synchronous transmission between the tube and the unwinding roller, and preventing the tube from slipping and spinning during unwinding. The limit pin restricts the maximum outward swing of the pawls to prevent the pawls from coming off the base, while ensuring that the pawls can lock and stop when rotating in the opposite direction, preventing the label roll from turning back and loosening.

[0058] The base includes: a disc-shaped main body and a cover disposed at the rear end of the disc-shaped main body for covering the disc-shaped main body; the elastic element is a compression spring.

[0059] An unwinding device includes a traction device and the aforementioned braking mechanism for tension control. A plurality of second guide wheels 51 are spaced apart on the mounting frame 31. The end of the label paper can be sequentially wound around the first guide wheel 39 and the plurality of second guide wheels 51 and connected to the traction device.

[0060] Specifically, the traction device is a relatively mature existing technology, and its structural principle will not be described in detail here. It can apply force to pull the end of the traction label paper along the first guide wheel and several second guide wheels to guide the displacement.

[0061] The label roll is mounted on the unwinding roller. The end of the label paper passes sequentially around several second guide rollers on the mounting frame and the first guide roller on the tension swing arm, and finally connects to the traction device. The traction device continuously pulls the label paper forward. The braking mechanism is based on the Euler principle of flexible body friction. It dynamically limits the rotation speed of the unwinding roller through friction braking, so that the label paper always maintains a stable tension. The tension swing arm swings back and forth with the fluctuation of the label tape tension. The linkage cam automatically adjusts the tension of the friction belt and the magnitude of the braking torque to ensure uniform tension and smooth label output throughout the unwinding process, effectively improving the labeling accuracy and the stability of continuous equipment operation.

[0062] The direction of the cam's pushing force on the second connecting block is opposite to the direction of the second tension spring's tension (effective tension force at the end of the friction band = tension force of the second tension spring - pushing force of the cam). When the cam's lift increases, the increase in pushing force is greater than the increase in the tension force of the tension spring itself, therefore the effective tension force of the friction band decreases net.

[0063] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A braking mechanism for tension control, characterized in that, include: Mounting bracket (31); Unwinding roller (32), which is rotatably mounted on mounting frame (31) for mounting label paper tubes; The braking mechanism includes a friction wheel (33), a friction belt (34), a first elastic member (35), and a second elastic member (36). The friction wheel (33) is mounted on the unwinding roller (32) and can rotate with the unwinding roller (32). The friction belt (34) can rub against the surface of the friction wheel (33). The first elastic member (35) and the second elastic member (36) are respectively connected to both ends of the friction belt (34) so ​​that the friction belt (34) and the friction wheel (33) maintain a frictional contact.

2. The braking mechanism for tension control according to claim 1, characterized in that: The braking mechanism also includes a tension swing arm (37), which is rotatably mounted on the mounting frame (31) via a rotating shaft (38). A first guide wheel (39) for the end of the label paper to be wound around is provided on the tension swing arm (37), and a cam (40) is provided at the rotating shaft (38). The cam (40) can rotate and press against the first elastic member (35) or the second elastic member (36) to release the tension at one end of the friction band (34). A third elastic member (41) is connected between the tension swing arm (37) and the mounting frame (31). The third elastic member (41) is used to keep the cam (40) in a disengaged state from pressing against the first elastic member (35) or the second elastic member (36).

3. A braking mechanism for tension control according to claim 1, characterized in that: The first elastic member (35) includes a first tension spring (42) and a first connecting block (43). The first connecting block (43) is connected to one end of the friction belt (34). The first tension spring (42) is connected between the first connecting block (43) and the mounting bracket (31), and the first tension spring (42) initially maintains a tension force on the first connecting block (43).

4. A braking mechanism for tension control according to claim 2, characterized in that: The second elastic member (36) includes a second tension spring (44) and a second connecting block (45). The second connecting block (45) is connected to one end of the friction belt (34), and the second connecting block (45) is mounted on the mounting bracket (31) by sliding the slide rail slider. The second tension spring (44) is connected between the second connecting block (45) and the mounting bracket (31), and the second tension spring (44) initially maintains a tension force on the second connecting block (45). The cam (40) can rotate and press against the second connecting block (45), causing the second connecting block (45) to move away from the second tension spring (44).

5. A braking mechanism for tension control according to claim 4, characterized in that: The second connecting block (45) is provided with a protrusion (46) that abuts against the wheel surface of the cam (40), and the second connecting block (45) is provided with an adjustment structure (47) that can adjust the protrusion (46) relative to its outward protrusion length.

6. A braking mechanism for tension control according to claim 5, characterized in that: The adjustment structure (47) includes a vertical long groove (48) that runs through the protrusion (46). The second connecting block (45) has two or more screw holes in the vertical long groove (48). Fastening screws are threadedly connected to the screw holes one by one. The fastening screws can be pressed onto the protrusion (46) along the thread displacement.

7. A braking mechanism for tension control according to claim 2, characterized in that: The third elastic component (41) includes a third tension spring (49) and a limiting post (50). The third tension spring (49) is connected between the mounting frame (31) and the tension swing rod (37). The limiting post (50) is located on one side of the mounting frame (31). The tension swing rod (37) is held in contact with the limiting post (50) by the tension of the third tension spring (49).

8. A braking mechanism for tension control according to claim 1, characterized in that: The friction wheel (33) is detachably installed at one end of the unwinding roller (32).

9. A braking mechanism for tension control according to claim 1, characterized in that: The unwinding roller (32) is provided with an anti-rotation mechanism; The anti-rotation mechanism includes a base (1), the center of which is provided with an installation through hole (10) for mounting on the unwinding roller (32), and a plurality of elastic pawl units are evenly arranged in the circumferential direction inside the base (1). The elastic pawl unit includes a pawl (21), a first hinge pin (22), a second hinge pin (23), a spring pin (24), and an elastic element (25); the first hinge pin (22) is mounted on the base (1), and its axis is arranged parallel to the central axis of the base (1); one end of the pawl (21) is hinged to the first hinge pin (22) and can swing inward and outward along the radial direction of the base (1); the second hinge pin (23) extends parallel to the first hinge pin (22) and passes through the part of the pawl (21) away from the first hinge pin (22) and between the second hinge pin (24); the pawl (21) is connected to the first hinge pin (22) by the second hinge pin (23). The hinge pin (23) can drive the spring pin (24) to move synchronously when swinging, and the pawl (21) and the spring pin (24) can rotate relative to each other around the second hinge pin (23); an elastic element (25) is provided between the spring pin (24) and the inner wall of the base (1), and the elastic pawl unit also includes a limiting pin (26). The limiting pin (26) is located on the radial outer side of the pawl (21) and is used to limit the maximum outward swing stroke of the pawl (21). The base (1) is provided with mounting grooves (11) corresponding to each elastic pawl unit. The mounting grooves (11) are open to the outer periphery of the base (1) so that the pawl (21) can swing outward.

10. An unwinding device, characterized in that, include: The traction device and the braking mechanism for tension control according to any one of claims 1-9, wherein a plurality of second guide wheels (51) are spaced apart on the mounting frame (31), and the end of the label paper can be sequentially wrapped around the first guide wheel (39) and the plurality of second guide wheels (51) and connected to the traction device.

Images